As shown in FIG. 6, in a liquid crystal display device using a COG (Chip On Glass) technology, a long flexible wiring substrate 5 (hereinafter, referred to as the FPC: Flexible Printed Circuit) extending in an x direction is connected to a liquid crystal panel 7 in many cases. In this case, a terminal-exposed part is made in a gap between a front-face coverlay end portion B (an end portion facing an end face of a glass substrate) of the FPC 5 and a chamfered area end portion D of the glass substrate of the liquid crystal panel 7 (refer to FIG. 1 of JP-A-2007-281378). Additionally, the symbol A is rear-face coverlay end portion located on a rear side, and the symbol E is an end portion of FPC located on a glass substrate side. In order to suppress corrosion of the exposed terminal (a plated part), a resin 24 is applied to the terminal-exposed part (refer to FIG. 5 of JP-A-2007-281378).
Meanwhile, in below descriptions, a “front-face” of the FPC 5 refers to a face on which a connection terminal (a conductor for wiring) 13a with the liquid crystal panel 7 is provided, and a “rear-face” refers to a face on which a coverlay 11 is provided.
As shown in FIG. 7, which is a sectional view as seen in a VII direction of FIG. 6, the three-layered FPC 5 of the background art has a layer configuration where coverlay adhesive layers 16 are provided between a front-face coverlay 10 and the panel connection terminal (a conductor for wiring) 13a and between the rear-face coverlay 11 and a base film 12 and base film adhesive layers 15 are provided on both faces of the base film 12 (refer to a paragraph [0050] of JP-A-2011-9270). Additionally, the liquid crystal panel 7 include a polarizing plate 1, and a color filter, and a glass substrate 4.
For a two-layered FPC in which an adhesive is not used, the base film adhesive layers 15 are not provided (refer to a paragraph [0027] of JP-A-2011-9270).
Here, a linear expansion coefficient of the glass, which is one substrate material of the liquid crystal panel 7 shown in FIG. 7, is about 4 ppm/K, general polyimide, which is used as the base film 12 and coverlays 10, 11 of the FPC 5, has a linear expansion coefficient of about 16 to 18 ppm/K, and the coverlay adhesive 16 or base film adhesive 15 adhering the base film and coverlays has a linear expansion coefficient of about 100 ppm/K, which is considerably larger than other linear expansion coefficients. As a result, in a case where FPC 5 is repeatedly shrank and expanded in a thermal shock test repeating low and high temperatures, the FPC 5 fixed to the glass substrate 4 is easily applied with stress at both ends in a W direction (a longitudinal direction of the FPC) of FIG. 6.